A Bean cDNA Expressed During a Hypersensitive Reaction Encodes a Putative Calcium-Binding Protein

Abstract

The hypersensitive reaction (HR) is an inducible plant response that is associated with disease resistance. It is characterized by rapid, localized cell death at the site of infection and is believed to inhibit the spread of invading pathogens. We have isolated a cDNA clone, designated Hra32 (for hypersensitive reaction associated), corresponding to an RNA transcript that accumulates in bean during an HR. The predicted protein product of the Hra32 cDNA is an approximately 17 kDa protein of 161 amino acids, with four putative EF-hand calcium-binding domains. The temporal pattern of Hra32 transcript accumulation correlated closely with the onset of the HR in bean after inoculation with incompatible Pseudomonas syringae pv. tabaci and pv. tomato and with tobacco necrosis virus. Hra32 transcript also accumulated in bean in response to compatible P. syringae pv. phaseolicola and was correlated with necrotic cell death associated with disease lesion formation. A more transient pattern of Hra32 transcript accumulation occurred in bean in response to general stimuli that did not result in the HR or host cell death. These treatments included infiltration with a P. syringae pv. tabaci Hrp- mutant, P. syringae pv. tabaci cells treated with kanamycin, Escherichia coli, P. fluorescens, or glutathione, and in response to wounding. Thus, there was differential accumulation of the Hra32 transcript in response to specific stimuli resulting in the HR, compared with general stimuli that did not result in cell death. We hypothesize that the Hra32 product may be a component of the pathway that leads to hypersensitive cell death.

Genes Encoding Calmodulin-binding Proteins in the Arabidopsis Genome

“…glycinea (18); and (vi) pooled bean leaf tissue undergoing hypersensitive response as a result of infiltration of Pseudomonas syringae pv. tabaci Pt11528 (19).…”

Tansley Review No. 118

“…Although herbivory damage usually concerns aphid or caterpillar attack, the generation of wound responses could be the same after cattle or sheep damage. Plant parts damaged by herbivory can produce a systemic wound response, localized proteolysis and necrosis (Jakobek et al, 1999 ;Rhodes et al, 1999 ;Suh et al, 1999). The response to wounding in detached plant parts might differ from that observed in intact plant parts.…”

“…In the field, plants are exposed to a variety of potentially pathogenic microorganisms and have developed species-specific degrees of tolerance and resistance (Greenberg, 1997 ;Morel & Dangl, 1997). The hypersensitive response can be generated in vitro by incubation of plant material with 10& cells ml −" of bacteria, with lesions appearing after 72 h (Jakobek et al, 1999). The observation that hypersensitive cell death does not occur in cell cultures (Honee et al, 1998) could be interpreted to dismiss the significance of hypersensitive response in plant tissue in the rumen.…”

Expression of a bean acid phosphatase cDNA is correlated with disease resistance

“…Red Kidney) leaf tissue undergoing an HR after infiltration with P. syringae pv. tabaci Pt11528 (Jakobek et al, 1999). This library was screened as previously described (Jakobek et al, 1999) using a combination of differential and cold-plaque screening to identify cDNAs corresponding to transcripts expressed during an HR.…”

“…tabaci Pt11528 (Jakobek et al, 1999). This library was screened as previously described (Jakobek et al, 1999) using a combination of differential and cold-plaque screening to identify cDNAs corresponding to transcripts expressed during an HR. During this process a cDNA clone, designated Hra28 (for hypersensitive reaction associated), was identified that is predicted to encode a novel acid phosphatase (GenBank Accession No.…”